<template>
	<view>
   <my-search @click="gotoSearch"></my-search>
    
		<view class="scroll-view-container">
      <!--  左侧的滑动区域 -->
		  <scroll-view class="left-scroll-view" scroll-y="true" :style="{height: windowHeight + 'px'}">
		    <block v-for="(item, i) in cateList" :key="i">
          <view :class="['left-scroll-view-item', i===active ? 'active' : '']" @click="activeChanged(i)">{{item.cat_name}}</view>
        </block>  
      </scroll-view>
      
      <!-- 右侧的滑动区域 -->
      <scroll-view :class="right-scroll-view" scroll-y="true" :style="{height: windowHeight + 'px'}" :scroll-top="scrollTop">
        <!-- 右侧二级分类列表 -->
        <view class="cate-lv2" v-for="(item2, i2) in cateLevel2" :key="i2">
          <!-- 二级分类的标题 -->
          <view class="cate-lv2-title">/{{item2.cat_name}}/</view>
          <!-- 动态渲染三级分类列表 -->
          <view class="cate-lv3-list">
            <!-- 三级分类 item 项 -->
            <view class="cate-lv3-item" v-for="(item3, i3) in item2.children" :key="i3" @click="gotoGoodsList(item3)">
              <!-- 图片 -->
              <image :src="item3.cat_icon" mode="widthFix"></image>
              <!-- 文本 -->
              <text>{{item3.cat_name}}</text>
            </view>
          </view>
        </view>
      </scroll-view>
		</view>
	</view>
</template>

<script>
  import badgeMix from '@/mixins/tabbar-badge.js'
  
	export default {
    mixins: [badgeMix],
		data() {
			return {
        // 设备可用窗口的高度
				windowHeight: 0,
        // 分类列表数据
        cateList: [],
        // 标记左侧滚动栏的选中项
        active: 0,
        // 二级分类列表
        cateLevel2: [],
        //右侧滚动条距离顶部的值
        scrollTop: 0
			}
		},
    onLoad() {
      const sysInfo = uni.getSystemInfoSync()
      // 扣除顶部搜索框的高度
      this.windowHeight = sysInfo.windowHeight - 50
      this.getCateList()
    },
    methods:{
      async getCateList() {
        const { data: res } = await uni.$http.get('/api/public/v1/categories')
        if( res.meta.status !== 200 ) return uni.$showMsg()
        this.cateList = res.message
        // 为二级分类赋值
        this.cateLevel2 = res.message[0].children
      },
      // 选中项改变的事件处理函数
      activeChanged(i) {
        this.active = i
        // 为二级分类重新赋值
        this.cateLevel2 = this.cateList[i].children
        // 让 scrollTop 的值在 0 与 1 之间切换（动态设置，保证一级菜单切换时，滚动条始终在顶部）
        // this.scrollTop = this.scrollTop === 0 ? 1 : 0
        this.scrollTop = this.scrollTop ? 0 : 1
      },
      // 跳转到商品列表页
      gotoGoodsList(item) {
        uni.navigateTo({
          url: '/subpkg/goods_list/goods_list?cid=' + item.cat_id
        })
      },
      gotoSearch() {
        uni.navigateTo({
          url: '/subpkg/search/search'
        })
      }
    }
	}
</script>

<style lang="scss">
.scroll-view-container {
  display: flex;
  .left-scroll-view {
    width: 120px;
  }
}
.left-scroll-view-item {
  background-color: #F7F7F7;
  text-align: center;
  line-height: 60px;
  font-size: 12px;
  //  选中项
  &.active {
    background-color: #FFFFFF;
    position: relative;
    
    &::before {
      content: '';
      display: block;
      width: 3px;
      height: 30px;
      background-color: #C00000;
      position: absolute;
      top: 50%;
      left: 0;
      transform: translateY(-50%);
    }
  }
}

.cate-lv2-title {
  font-size: 12px;
  font-weight: bold;
  text-align: center;
  padding: 15px 0;
}

.cate-lv3-list {
  display: flex;
  flex-wrap: wrap;
  
  .cate-lv3-item {
    width: 33.33%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    margin-bottom: 10px;
    image {
      width: 60px;
      height: 60px;
    }
    text {
      font-size: 12px;
    }
  }
}
</style>
